1960 390 Vacuum Advance

oregonjam · June 21, 2019, 01:00:58 PM

Something must be incorrect...

I just finished reinstalling the engine. I ran the lines and had a Vac leak at the hard line Vacuum advance from distributor to carburetor base at the front. I have a 390 with a Carter 4 barrel. The vac advance hard line has a male threaded barb and the the line goes through the middle with a flare. The carb has a threaded hole. If I tighten down the line until the male fitting seats all the way against the carb base, the line can still be moved in and out. There is nothing inside the carb base to seat the flared line, so there is a vacuum leak. I temporarily put gasket maker on the tube to male end to seal it which worked.

Does anyone know if there is a part that should screw into the carb base to provide a seat for the flare fitting? If not how did the advance line seal?

So close to being back on the road. Let me know what you think. Any help is appreciated.

oregonjam · June 21, 2019, 01:17:54 PM

here is an image to be more clear. It is not threaded in all the way in this image but will bottom out without sealing.

Dan LeBlanc · June 21, 2019, 02:02:36 PM

You're definitely missing the brass fitting that screws onto the carburetor body with the seat in it for the flare.

oregonjam · June 21, 2019, 02:24:54 PM

Dan,

Thank You. makes total sense now that I see it. I will correct it.

Cheers,
John

Big Fins · June 21, 2019, 04:16:43 PM

John...
On your picture, you have a hole on the exhaust crossover. The hole is an internal tube which rots away and it connects to the choke heater via that threaded male fitting that you see right under the word 'Climatic' on the adjusting (rich/lean) housing. The distributor vacuum advance line runs to a fitting on the back of the carb base.

I have a 59 Rottenchester in the garage. Lemme see if I can get a picture for you.

Look at the picture.

oregonjam · June 21, 2019, 04:59:30 PM

Big Fin,

Thank you for the details. Yes the picture I have shared does not show the carb completely installed yet. There are no nuts on the carb mount studs etc. I was fitting and checking lines at the time.

That said, here is what I have: (as I understand it) The factory pre-bent hard-line for the vacuum advance on the carter carb goes to the front in 1960. However, I am confused by the preheat cross over. I do not have a line hooked up to that. I do have a line that runs from a hole on the top of the exhaust manifold to the carb side that you are showing hooks up to the crossover preheat tube. I can locate a tube to run it properly if that is how it is supposed to be, However what is the hole in exhaust manifold for? Photo below...

thank You , John

Big Fins · June 22, 2019, 05:05:24 AM

That fitting in the exhaust manifold is something that I haven't seen. I'm wondering if it was a way to bring heat up to the choke heater after the intake tube rotted internally.

The pic I displayed still shows the engine with the Carter on it.

oregonjam · June 22, 2019, 08:51:41 AM

Yup in closer inspection it looks like it was a kit. Drill a hole in the exhaust manifold and the part shown has cutting threads on it with a lead in. Below that it extends down without threads, smooth exterior to collect heat. It has a blind hole through the bolt head to insert a pipe and the flat side of the bolt head are cross drilled. I assume someone installed it after having an issue preheating. The intake heat tube isnâ€™t rotted but it was clogged and wouldnâ€™t function.

I showed a friend and he said that he has seen that on other motors previously.

I will correct it. Thanks for the help.

Weird on the carter the vac advance def goes on the front. Were the carters different in other years?

Thanks, john

Roger Zimmermann · June 23, 2019, 07:02:52 AM

With that arrangement, the exhaust gases will be allowed to go into the choke, which is no good at all. The choke will be disabled rather quickly.
The person who did that had absolutely no competence.

Big Fins · June 23, 2019, 07:47:25 AM

In reality, it's the same as the intake heater tube. The choke adjusting cap on the side of the carb has a very small vacuum draw. Open any of them up and you will see soot in them. This comes from the tube rotting out inside the crossover. IIRC, it goes straight through and the vacuum draw which is so small simply draws air up through the tube. The new S/S tube lasted maybe 2 years.

I got so frustrated with the sooting up of the choke stove that I bought intake gaskets with the crossover block and put on an Edlebrock with an electric choke. I never looked back

News:

1960 390 Vacuum Advance